From 40ad7ed67e16ce3ca6107f9b169055730d9975b1 Mon Sep 17 00:00:00 2001
From: adelikat <adelikat@tasvideos.org>
Date: Sun, 12 Jul 2020 12:58:39 -0500
Subject: [PATCH] Lua - account for callbacks with no parent script creating
 more callbacks by generating a mock lua file with a new thread, and register
 the thread with the sandbox.  Fixes #1983.  Not super proud of this.

---
 .../lua/LuaHelperLibs/EventsLuaLibrary.cs     |  8 +++----
 .../lua/NamedLuaFunction.cs                   | 23 ++++++++++++++++++-
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/src/BizHawk.Client.Common/lua/LuaHelperLibs/EventsLuaLibrary.cs b/src/BizHawk.Client.Common/lua/LuaHelperLibs/EventsLuaLibrary.cs
index 43a2b89740..58f5a2b995 100644
--- a/src/BizHawk.Client.Common/lua/LuaHelperLibs/EventsLuaLibrary.cs
+++ b/src/BizHawk.Client.Common/lua/LuaHelperLibs/EventsLuaLibrary.cs
@@ -48,7 +48,7 @@ namespace BizHawk.Client.Common
 
 		public void CallSaveStateEvent(string name)
 		{
-			var lfs = RegisteredFunctions.Where(l => l.Event == "OnSavestateSave");
+			var lfs = RegisteredFunctions.Where(l => l.Event == "OnSavestateSave").ToList();
 			try
 			{
 				foreach (var lf in lfs)
@@ -64,7 +64,7 @@ namespace BizHawk.Client.Common
 
 		public void CallLoadStateEvent(string name)
 		{
-			var lfs = RegisteredFunctions.Where(l => l.Event == "OnSavestateLoad");
+			var lfs = RegisteredFunctions.Where(l => l.Event == "OnSavestateLoad").ToList();
 			try
 			{
 				foreach (var lf in lfs)
@@ -80,7 +80,7 @@ namespace BizHawk.Client.Common
 
 		public void CallFrameBeforeEvent()
 		{
-			var lfs = RegisteredFunctions.Where(l => l.Event == "OnFrameStart");
+			var lfs = RegisteredFunctions.Where(l => l.Event == "OnFrameStart").ToList();
 			try
 			{
 				foreach (var lf in lfs)
@@ -96,7 +96,7 @@ namespace BizHawk.Client.Common
 
 		public void CallFrameAfterEvent()
 		{
-			var lfs = RegisteredFunctions.Where(l => l.Event == "OnFrameEnd");
+			var lfs = RegisteredFunctions.Where(l => l.Event == "OnFrameEnd").ToList();
 			try
 			{
 				foreach (var lf in lfs)
diff --git a/src/BizHawk.Client.Common/lua/NamedLuaFunction.cs b/src/BizHawk.Client.Common/lua/NamedLuaFunction.cs
index 7174108dfa..089e9949cc 100644
--- a/src/BizHawk.Client.Common/lua/NamedLuaFunction.cs
+++ b/src/BizHawk.Client.Common/lua/NamedLuaFunction.cs
@@ -14,7 +14,28 @@ namespace BizHawk.Client.Common
 			_function = function;
 			Name = name ?? "Anonymous";
 			Event = theEvent;
-			LuaFile = luaFile;
+
+			// When would a file be null?
+			// When a script is loaded with a callback, but no infinite loop so it closes
+			// Then that callback proceeds to register more callbacks
+			// In these situations, we will generate a thread for this new callback on the fly here
+			// Scenarios like this suggest that a thread being managed by a LuaFile is a bad idea,
+			// and we should refactor
+			if (luaFile == null)
+			{
+				var thread = new Lua();
+				
+				// Current dir will have to do for now, but this will inevitably not be desired
+				// Users will expect it to be the same directly as the thread that spawned this callback
+				// But how do we know what that directory was?
+				LuaSandbox.CreateSandbox(thread, ".");
+				LuaFile = new LuaFile(".") { Thread = thread };
+			}
+			else
+			{
+				LuaFile = luaFile;
+			}
+
 			Guid = Guid.NewGuid();
 
 			Callback = () =>